How do I know if the signal is E.M.E. ?

[VK2HCC]

It's probably a silly question, but how do yo know that a received signal is actually EME and hasn't followed some other path from sender?

Thanks
Craig

[VK3DXE]

The first step is to make sure your computer time is correct. A lot of people use Dimension 5 to keep their clock up to date, although under Windows 7 I'm having to rely on the Windoze time sync until I get time to sort it.

If a signal is off the moon, then you should expect to see about a 2.5 second delay on it, so in JT65 you'll see the "DT" field should have a value of around 2.5. A troppo signal will usually give a value of closer to zero. I know that my radio is pretty close to spot on once it's really warmed up, but when it's cold, it can be as much as 50Hz out at 2m.

WSJT also calculates the expected doppler on the signal, so provided your radio is on frequency and the other guy's is too, you can generally expect to see the signal at the appropriate frequency. If you're also receiving a signal direct (more common in places like Europe), then you might see the two traces. It's quite a buzz when you have an audible signal and you know the other guy stopped transmitting a couple of seconds ago, but you're still hearing the return from the moon. It gives you a good perspective of the distances involved.

The contact below was with a 4 x 10 el station running about 800watts. With ground gain, sometimes he's speaker copy with me on my single yagi.

[VK2KRR]

Hi Craig,

There is numerous details left out of your question that would help us to provide an answer.

Is there a signal you have seen that prompted this question? if so, whats the details, callsign, what band etc?

If the station is in Europe for example, your not going to get them from another path on 2m. When the moon sets the signal will not be present any longer.

If its a station in Australia in tropo range, if your pointing at them and not the moon and still get the signal then its likely tropo.

If your pointing at the moon and hearing them, as Alan said, there should be a timing difference and possible slight freq doppler shift in comparison to the direct signal.
Or it could just be its coming in on the side of the antenna etc from the direct path.

Or it could be false decodes...

To many variables.

[VK2HCC]

Thanks for the responses, I'm not setup here to try any EME it was just a general question/ thought I had. I do use WSJT a fair bit but never looked at the time delay fields.
Just having a look at Alan's screen shot and I have seen the double signal before but just assumed it was another stations signal also being picked up ( better read the manual a bit more)

Thanks for the info guys

[VK3DXE]

What you might think is a double signal could also be a birdie. 2KM from Melbourne CBD, the band is full of them